The present invention relates generally to motor vehicle wheel alignment and, more specifically, to providing a vehicle position adjustment mechanism for positioning a vehicle in different positions for applications such as using a 3D machine vision measuring system for alignment.
Motor vehicle alignment systems are important for ensuring that the alignments of wheels on a vehicle are within the specifications provided by motor vehicle manufacturers. If the wheels are out of alignment, there may be excessive or uneven wear. In addition, the performance of the vehicle, particularly handling and stability, may be adversely affected if the wheels are not properly aligned. As used herein, the term xe2x80x9cwheelxe2x80x9d or xe2x80x9cvehicle wheelxe2x80x9d refers to the tire and wheel assembly found on a motor vehicle. Such an assembly generally includes a conventional tire that is mounted on a metal wheel or xe2x80x9crim.xe2x80x9d
The wheels of a motor vehicle may be aligned in a number of ways. For example, an operator or an alignment technician can use a vision imaging system such as a computer-aided, three-dimensional (3D) machine vision that employs optical sensing devices, such as cameras, to determine the positions of various objects. Although such machine vision systems are typically used for alignment purposes, these systems can also be used to obtain other positional and angular orientation information about a motor vehicle. Examples of such apparatus and methods are disclosed in U.S. Pat. No. 5,724,743, entitled xe2x80x9cMethod and Apparatus for Determining the Alignment of Motor Vehicle Wheels,xe2x80x9d issued to Jackson, et al. on Mar. 10, 1998 and in U.S. Pat. No. 5,535,522, entitled xe2x80x9cMethod and Apparatus for Determining the Alignment of Motor Vehicle Wheels,xe2x80x9d issued to Jackson, et al. on Jul. 16, 1996, each incorporated herein by reference. The apparatus disclosed in these patents is sometimes called a xe2x80x9c3D alignerxe2x80x9d or an xe2x80x9caligner,xe2x80x9d hereinafter referred to as a vision imaging system. As used herein, the term xe2x80x9cposition determination systemxe2x80x9d refers to an alignment system, such as the vision imaging system, in addition to other components used in conjunction with the alignment system to obtain positional and angular orientation information about a motor vehicle.
An example of a position determination system is illustrated in FIG. 1. The position determination system 100 includes a vision imaging system 102 having a pair of fixed, spaced-apart cameras 110, 112 mounted on a beam 114. The beam 114 has a length sufficient to position the cameras 110, 112 respectively outboard of the sides of any vehicle to be aligned by the position determination system 100. Also, the beam 114 positions the cameras 110, 112 high enough above the shop floor 116 to ensure that the two targets 118, 120 on the left side of the vehicle are both within the field of view of the left side camera 110, and two targets 122, 124 on the right side of the vehicle are both within the field of view of the right side camera 112.
Targets 118, 120, 122, 124 are mounted on each of the wheels 126, 128, 130, 132 of the motor vehicle, with each target 118, 120, 120, 124 including a target body 134, target elements 136, and an attachment apparatus 138. The attachment apparatus 138 attaches the target 118, 120, 120, 124 to wheel 126, 128, 130, 132. An example of an attachment apparatus is described in U.S. Pat. No. 5,024,001, entitled xe2x80x9cWheel Alignment Rim Clamp Clawxe2x80x9d issued to Borner et al. on Jun. 18, 1991, incorporated herein by reference. The target elements 136 are positioned on the target body 134. Examples of target bodies 134 and target elements 112 acceptable for use in the invention are described in U.S. Pat. No. 5,724,743.
In operation, once the position determination system 100 has been calibrated using a calibration target (not shown), as described in the incorporated references, a vehicle can be driven onto the rack 133, and, if desired, the vehicle lifted to an appropriate repair elevation. The targets 118, 120, 122, 124, once attached to the wheel rims, are then oriented so that the target elements 136 on the target body 134 face the respective camera 110, 112. The vehicle and model year can then entered into the vision imaging system 102 along with other identifying parameters, such as vehicle VIN number, license number, owner name, etc.
The location of the targets 118, 120, 122, 124 relative to the rim of the wheels 126, 128, 130, 132 to which the targets are attached are typically known to an accuracy of about 0.01xe2x80x3 and about 0.01xc2x0. Once the targets 118, 120, 122, 124 have been imaged in one position, the wheels 126, 128, 130, 132 are rolled to another position and a new image can be taken. Using the imaged location of the targets 118, 120, 122, 124 in the two positions, the actual position and orientation of the wheels 126, 128, 130, 132 and wheel axis can be calculated by the vision imaging system 102. Although the distance between the two positions varies, the distance is often approximately 8 inches.
A problem associated with moving the vehicle to the different positions during use of the position determination system is that the vehicle must be manually pushed from one position to next position. This pushing of the vehicle takes considerable strength. If, for example, the car is particularly heavy or the technician pushing the car has insufficient strength, the technician may be unable to roll or safely roll the vehicle between the two positions. There is, therefore, a need for an apparatus for positioning the vehicle to be measured by the position determination system that does not require a particular level of strength in the technician doing the measurements. Furthermore, there is a need for an apparatus that accurately rolls the vehicle into the positions in which images of the targets are taken. This need arises as well for non-vision type alignment and other applications requiring a vehicle to be rolled for relatively short distances.
This and other needs are met by the present invention, which in accord with one aspect includes a position determination system and a vehicle position adjustment mechanism. The position determination system obtains positional information about a vehicle and can include a vision imaging system and the vehicle position adjustment mechanism. The vehicle position adjustment mechanism moves the vehicle into at least two positions for imaging by the vision imaging system. The vehicle position adjustment mechanism includes a body for engaging the vehicle and a controller to control the direction and distance the vehicle position adjustment mechanism moves the vehicle. The controller can communicate with the vision imaging system. Also, the vehicle position adjustment mechanism can further include surface support wheels connected to the body for supporting the body on a surface and a motor for driving the vehicle into the at least two positions.
By providing a vehicle position adjustment mechanism that moves a vehicle into at least two position for imaging by a vision imaging system, a technician operating the position determination system can position the vehicle without the need for excess physical exertion. Additionally, the operator can control the movement of the vehicle within a positional tolerance acceptable for the vision imaging system through use of the controller. A typical movement of the vehicle is 8 inches back from an initial starting point and then 8 inches forward to the initial starting point.
The vehicle position adjustment mechanism can include surface support wheels that are connected to the body for supporting the body on a surface. Vehicle support wheels for engaging the vehicle wheel can also be provided. Also, the vehicle position adjustment mechanism can include a motor driving at least one of the vehicle support wheels and the surface support wheels to drive the vehicle into the at least two positions.
The body surrounds and engages a vehicle wheel of the vehicle, and includes a cavity into which the vehicle wheel is inserted for engagement. The body can also include an open end through which the vehicle tire can be inserted into the cavity. The body can also include such features as joints for allowing the body to be separated and a width adjuster to adjust the width of the cavity.
In an alternative aspect, the body includes an engaging arm for engaging the vehicle with the engaging arm extending from the base. The engaging arm can also include an attachment device to connect the engaging arm to the vehicle.
In still another alternative aspect, the body includes an engagement device for engaging the vehicle, an attachment device for attaching the body to rails on a rack, and a motor for driving the attachment device along the rails. The rack, for example, can be an alignment rack, and the engagement device, for example, can be an air bladder. Also, the attachment device can be a rack and pinion system.
Additional advantages of the present invention will become readily apparent to those skilled in this art from the following detailed description, wherein only an exemplary embodiment of the present invention is shown and described, simply by way of illustration of the best mode contemplated for carrying out the present invention. As will be realized, the present invention is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the invention. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.